With the popularization of mobile terminals, demands for realizing electronic payments using the mobile terminals become very urgent. Nowadays, the electronic payment technology has a variety of implementations. One of the implementations is realized through integrating a 2.4 GHz radio frequency (RF) communication module, a magnetic coupling coil and a magnetic induction processing module in a mobile phone SIM (Subscriber Identity Model) card or SD (Secure Digital) Card. In this type of implementation, through detecting strength of a magnetic coupling signal and receiving magnetic channel information by the SIM card or SD card installed in the mobile phone, the 2.4 GHz radio frequency communication module integrated in the SIM card or SD card is activated and data transaction communication is performed. Because the magnetic coupling signal energy in the space attenuates with the distance to the third power and has a very good consistency for different mobile phones, so this implementation realizes RF high-speed data exchange and effectively controls RF data communication distance of the SIM card or SD card on a variety of mobile phone terminals, thus becoming a reliable mobile terminal electronic payment solution. In addition, the entire receiving and processing system is integrated in the SIM card or SD card and no modification for the mobile phone terminal is needed, so it has excellent application promotion value. However, due to absence of appropriate protective measures, when data transactions are performed, current RF channel parameters may be obtained by an attacker through analysis, so as to establish a connection with the activated RF card, thus raising security risks.